Optical fiber is a flexible, transparent fiber made-up of very pure glass and associated with the transmission of information as light pulses between the two ends of the fiber. Optical fiber carries much more information than conventional copper wire and in general it is not subjected to electromagnetic interference and signal loss during transmission. Optical fibers have shown great promise in communication and networking applications because it is flexible and can be bundled as cables. It is especially advantageous for long distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. Optical fiber can be very delicate. This creates problems in winding and unwinding operation in optical fiber packages such as canisters.
It is well-known that an adhesive binder is often used to stabilize filamentary structure packages, such as electrical cable and metal wire coil packages. In some specialized applications, the adhesive binder is not only to stabilize the package, but also to control the fluent payout of the filament and also to protect the filament for long life durability. An adhesive binder is usually applied on to the optical fiber or to each fiber layer by layer. The adhesive binder must be compatible with the fiber, which may otherwise cause total damage to the fiber during storage and payout, causing increased optical loss in the fiber or total damage such as crazing due to stress corrosion. The binder must also contribute in solving the problems faced in preparing and using optical fiber canisters. Some such problems are non uniform winding, small gaps, voids, bends and the like.
Several polymeric adhesive binders for optical fiber packages are reported in the prior art, such as Israeli patent 92130; Discloses adhesive composition comprising 5% of an adhesive consisting of one-fourth of 3,3,3-trifluoropropylmethylsiloxane and three-fourths of a polydimethylsiloxane, and 95% of carrier which is a trichlorotrifluoroethane or a trichloroethane or a mixture thereof.
U.S. Pat. No. 6,103,375 discloses adhesive binder composition for optical fiber packages consisting essentially of two parts; “Part A”, which is a blend of silicone polymer and epoxy resin, and “Part B”, which consist of three components: catalyst for silicone, epoxy curing agent and wetting agent for adhesion improvement. A methacrylic silane wetting agent is added to said components and whole mixture is dissolved in a organic solvent.
U.S. Pat. No. 5,532,320 discloses interpenetrating polymer network which can exhibit non linear optical properties comprising crosslinked polymer network of epoxy based first polymer and phenoxy silicon based second polymer.
Adhesive composition disclosed in above prior art is associated with some serious problems. Prior art adhesive creates difficulties when fiber has to be unwound or paid out from the canister. On many occasions, when the fiber is unwound, the adhesives adhere to the fiber too strongly to cause increased wind resistance or local impacts, when the fiber is deployed. This results in undesirable tension and bending in the fiber. This causes stress concentration and breakages, which means a total failure of the system.
The adhesive binders reported in the prior art contain strong solvents such as trichlorotrifluroethane, or a trichloroethane or their mixtures, and also mixtures of toluene, methylethylketone. All these solvents, as alone or their mixture dissolves the primary and secondary coating of the optical fiber, which results into light loss, and attenuation of the signal.
There is need for an improved adhesive for use in optical fiber winding and payout operations. Such adhesive should have sufficient bond strength and durability to hold the fiber in place during the long term storage without maintenance, flight, and unwinding operation. Also it must not interfere with the fiber unwinding, and hold the fiber layers in place and must allow the fiber to be paid out from the package easily and regularly.
The present invention provides an optical fibre package comprising an adhesive which effectively improves optical fiber winding, particularly as to their stability on long range exposures and payout properties, and improves the performance of the packages thus obtained. Present invention also eliminates the problems associated with prior art optical adhesive binders.